The present invention relates to hitches for towed implements and more specifically a relates to self-leveling hitch and clevis arrangements adapted for being hitched to a tractor drawbar.
Tractor drawn implements, of which a pull-type rotary cutter is one example, require the implement hitch to be coupled to the tractor drawbar in such a way as to allow for rotation in three directions (turning, twisting and pitching). To accommodate pitching, a horizontal pivot is required which in turn allows the clevis to hang down resulting in chucking and excessive clevis/drawbar wear. Chucking can also cause premature driveline failures. Two examples of designs which attempt to address these problems are respectively disclosed in U.S. Pat. No. 3,998,471 granted to Luchemeier on Dec. 21, 1976, and in U.S. Pat. No. 5,386,680 granted to Friesen on Feb. 7, 1995.
On some cutters, a link is pivotally attached between the mower deck and the clevis so as to form a parallel linkage with the hitch, thus resulting in the clevis being self-leveling as the cutter is raised and lowered, but this system does not allow for rotation during twisting or pitching except for the clearance between the drawbar pin and the slots in the clevis. With self-leveling, the clevis still rotates on the drawbar resulting in drawbar wear.
According to the present invention, there is provided an improved hitch and clevis assembly which overcomes the drawbacks associated with prior art hitch and clevis assemblies.
A object of the invention is to provide a self-leveling levis which does not include a separate link for keeping the clevis level.
A more specific object of the invention is to provide a hitch that has separate arms that are coupled between the towed implement frame and the clevis so as to define a parallel linkage that maintains the clevis in a level attitude.
Yet another object of the invention is to provide a hitch and self-leveling clevis assembly which operates such as to permit the clevis to rotate in three directions at its connection with the drawbar.
A further specific object of the invention is to provide a hitch and self-leveling clevis assembly, as set forth in the immediately preceding object, wherein the clevis includes upper and lower halves having opposed surfaces shaped complementary to and engaging a hitch ball containing a vertical hitch pin receiving hole and a horizontal opening adapted for receiving the drawbar of a tractor, whereby the ball provides a surface on which the clevis is pivotable in three directions.
These and other objects will become apparent from a reading of the ensuing description together with the appended drawings.